this is my code:

def a():
    print 'sss'

@a()
def b():
    print 'aaa'

b()

and the Traceback is:

sss
Traceback (most recent call last):
  File "D:\zjm_code\a.py", line 8, in <module>
    @a()
TypeError: 'NoneType' object is not callable

so how to use the '@'

thanks

updated

class a:
    @property
    def b(x):
        print 'sss'

aa=a()
print aa.b

it print :

sss
None

how to use @property

thanks